Ordinarily, a bicycle saddle is mounted on the top end of a saddle post slidably inserted in a vertical pipe of the frame of a bicycle. By fixing the saddle post to the vertical pipe with a clamp, the saddle can be locked in position at a desired height.
During traveling, the saddle is preferably at a higher position so that the rider can more easily apply force to the pedals. When the bicycle comes to a stop, the saddle is preferably at a lower position so that the rider can more easily and safely put a foot on the ground. But conventional height adjustment mechanisms as described above do not allow height adjustment of the saddle during traveling.
Many devices have therefore been proposed which can raise and lower the saddle during traveling. A typical such device includes a spring that biases the saddle upwardly, and a shock absorber for curbing a sharp rise and lowering of the saddle. By operating a switchover member on the handlebar, the saddle can be selectively locked at any height and moved.
The present applicant also proposed a bicycle saddle lifter in Patent document 1, which comprises a shock absorber having a cylinder as a fixed pipe inserted in a vertical pipe of a bicycle, and a piston as a lifting rod carrying a saddle on top thereof, a link coupling the fixed pipe to the lifting rod, and a stroke spring that biases the saddle upwardly.
In one embodiment, this device further includes ratchet pawls for checking descent and ascent of the saddle, respectively, and corresponding ratchet gears, wherein the ratchet pawls and the ratchet gears are mounted at a portion where upper and lower link pieces forming the link are coupled together.
In this device, when the switchover member on the handlebar is operated, the respective ratchet pawls are selectively brought into or out of engagement with the corresponding ratchet gears for switchover between a state where the saddle is allowed only to ascend and prevented from descending from a locked position at a predetermined height and a state where the saddle is allowed only to descend and prevented from ascending from a locked position at a predetermined height.
In order to ensure reliable switchover between the above two states and reliable engagement, the tips of the respective ratchet pawls and the valleys of the respective ratchet gears both have an angle of 90°.
Patent document 1: JP Patent Publication 2006-27497A